Technical Field
The present invention relates to a process for blocking fluid flow in a soil, and more particularly to a process for placing a foamed gel in a soil to reduce the flow capacity of a soil to a migratory fluid.
Description of Related Art
A number of gels are known in the art capable of blocking the flow of water through geological material. U.S. Pat. No. 4,521,452 teaches rigid gels positionable in near-surface soils that function as grout, thereby reducing the infiltration of water into man-made structures adjacent to the soils, such as tunnels or sewer lines. U.S. Pat. No. 4,582,452 teaches an aqueous gel positionable in relatively deep subterranean geological formations, such as consolidated geological matrix, to prevent the flow of underground water therethrough. Such gels have particular utility in oil production or subterranean construction applications.
In certain specific subterranean permeability-reduction applications, foamed gels have been successfully substituted for conventional unfoamed gels, thereby substantially reducing the chemical cost of the treatment without substantially diminishing the effectiveness of the treatment. For example, U.S. Pat. No. 5,322,125 employs a foamed gel to mitigate the inhibiting effect on oil production of gas coning in a formation having a gas cap overlying the oil production zone. The foamed gel is placed in the gas permeable matrix between the gas cap and production wellbore to reduce the flow of gas from the gas cap into the wellbore. Although such foamed gels effectively reduce the permeability of relatively deep formation matrices to migratory gases, foamed gels heretofore have not been considered applicable to near-surface soil sealing applications. Soils are generally less consolidated and more porous than matrix materials found in deeper formations. It is conventionally believed that foamed gels lack sufficient structure, strength and stability to perform effectively as soil sealants due to the relatively exposed and unconsolidated nature of soils. In particular, it is widely believed that foamed gels are more susceptible to degradation than conventional gels when exposed to the near-surface environment and further that foamed gels are more susceptible to mobilization than conventional gels when subjected to migratory liquids in unconsolidated soils. Thus, foamed gels have heretofore been deemed ineffective for soil sealing applications.
The present invention, nevertheless, recognizes a need for alternate materials as substitutes for conventional gels to effectively block the flow of migratory fluids through soils in a wide range of near-surface applications. In particular, the present invention recognizes a need for alternate soil sealing compositions that have sufficient structure, strength and stability to be relatively immobile in soil when subjected to the natural drift pressure of migratory liquids flowing therethrough, yet have a relatively low chemical cost as compared to conventional gels.
Accordingly, it is an object of the present invention to provide a soil treatment process for blocking the flow of migratory fluids in soil. It is another object of the present invention to provide such a soil treatment process that is operationally facile and economical. It is also an object of the present invention to provide such a soil treatment process that utilizes an effective fluid blocking composition. It is further an object of the present invention to provide such a soil treatment process that utilizes a relatively low cost and environmentally compatible fluid blocking composition.